SPECTROSCOPIC PROPERTIES OF CR4+-DOPED LIALO2

The spectroscopic properties of the new potential laser material Cr4+: LiAlO2 are presented. LiAlO2 exhibits tetrahedrally coordinated lattic e sites only. Doping the crystal with chromium only as well as additio nal codoping with magnesium yields the incorporation of Cr4+ On the Al site. The Cr4+ emission extends from 1.1 to 1.7 mu m. In the case of doping just with chromium, the lifetime is single exponential in the w hole temperature range between 12 and 550 K with a room-temperature li fetime of 29 mu s and a low-temperature lifetime of 95 mu s, which are the longest lifetimes observed until now for Cr4+ systems. Codoping w ith magnesium yields an additional Cr4+ center, which is clearly obser ved both in the decay dynamics and in the low-temperature emission spe ctrum.